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Physics > Chapter 19 - Stars > Flashcards

Chapter 19 - Stars Flashcards

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1
Q

What is a nebulae?

A

Gigantic cloud of dust and gas (mainly hydrogen), can be many many times bigger than our solar system

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2
Q

Do nebulae form quickly?

A

No, over millions of years

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3
Q

How do nebulae form?

A

The tiny gravitational attraction between particles of dust and gas, pull all the particles together to form a cloud

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4
Q

What happens as the dust and gas get closer together?

A

The gravitational collapse accelerates

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5
Q

How do denser regions form?

A

Due to tiny variations in the the nebulae, denser regions are apparent and these regions pull in even more dust and gas (only getting denser)

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6
Q

Why would the heat of the denser regions change?

A

They get hotter due to more gravitation energy being converted to thermal energy

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7
Q

What is a protostar?

A

One of the denser regions of a nebulae - very hot and very dense sphere of dust and gas

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8
Q

What must a protostar do to become a normal star?

A

Nuclear fusion must start in it’s core

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9
Q

What conditions are needed for nuclear fusion in a protostar’s core?

A

Extremely high temperatures and pressures to overcome the electrostatic repulsion between hydrogen nuclei

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10
Q

What do fusion reactions produce?

A

Kinetic energy

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11
Q

What happens for a protostar continuously gaining mass, so hot and provided enough KE to overcome the electrostatic repulsion?

A

Hydrogen nuclei are forced together to make helium nuclei, nuclear fusion begins, a star is made

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12
Q

How does a star remain in an equilibrium with a roughly constant size?

A

Gravitational forces compress the star, but the radiation pressure and gas pressure push the star outwards, balancing the forces out

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13
Q

Where does radiation pressure come from?

A

From the photons emitted during fusion

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14
Q

Where does gas pressure come from?

A

From the nuclei in the core

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15
Q

What is a star - in this equilibrium - stage of life called?

A

The main sequence

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16
Q

What effects how long a star stays on the main sequence?

A

The mass and size of its core, the more mass = the more power it releases and the quicker it undergoes fusion = shorter life

17
Q

What stars are likely to have a shortish life?

A

Massive supergiants, much hotter and bigger than others

18
Q

Description of a planet?

A

An object in orbit around a star, with three characteristics

19
Q

Characteristic of a planet - concerning its mass?

A

It has a large enough mass so that its own gravity allows a spherical shape to form

20
Q

Characteristic of a planet - concerning reactions?

A

It does not carry out nuclear fusion

21
Q

Characteristic of a planet - concerning its orbital path?

A

It has most likely cleared its path of any other objects previously there e.g. asteroids

22
Q

What is the difference between a planet and a dwarf planet?

A

Dwarf planets have not cleared there orbital paths of other objects unlike planets

23
Q

Description of an asteroid?

A

Objects too small or uneven to be a planet, in near circular orbit around the sun (without the ice present in comets)

24
Q

What is a planetary satellite?

A

Any body in orbit around a planet e.g. moons/man made satellites

25
Q

Description of a comet?

A

Small irregular bodies made of ice/rock/dust, all comets orbit the sun in eccentric elliptical orbits, the release a gas ‘tail’ when near the sun

26
Q

Description of solar systems?

A

Our solar system contains the sun, planets and any other objects that orbit either of these

27
Q

What is a galaxy?

A

A collection of stars and interstellar dust and gas - a large amount of these stars have their own solar systems

28
Q

Our galaxy?

A

The milk way

29
Q

Vague description of our universe?

A

Electromagnetic radiation, energy, matter, space-time = everything

30
Q

What is Orion?

A

One of the most recognisable constellations - containing stars at different points in their lifecycle

31
Q

What is a constellation?

A

A group of stars

32
Q

What is solar mass?

A

The mass of the sun - 1.99 x10^30

33
Q

What happens to stars with low mass when they run out of hydrogen fuel?

A

They move off of the main sequence into the next phase of their life

Physics (10 decks)

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